The overall goal of this program project grant (PPG) is to explore the cellular and molecular mechanisms of allogeneic bone marrow transplantation (BMT) and to serve as a translational research platform for novel therapeutic strategies for patients with hematologic malignancies. Graft versus host disease (GVHD) remains a major cause of morbility and mortality after allogeneic BMT and prevents this curative therapy from wider application in cancer patients; thus a long term goal for the entire area of BMT is to develop new strategies to separate a beneficial graft versus leukemia (GVL) effect GVL from GVHD. This PPG contributes to that goal by: 1) exploring the cellular and molecular mechanisms of GVHD; and 2) functioning as a translational research platform by applying these mechanistic insights in Phase I/II clinical trials in BMT patients. The significance o f these studies therefore Iies in their potential to lead to novel therapies for cancer patients, particularly those with hematologic malignancies. The major theme of this PPG is the modulation of donor immune responses to allogeneic host tissues without removal of T cells from the donor graft. This theme of cytokine dysregulation in GVHD develops in several ways and unifies the entire PPG increasing collaborations and interactions among project leaders and provides multiple opportunities for synergy. The PPG consists of three projects and two cores: Regulation of Premature Keratinocyte Apoptosis in GVHD Cytokine Modulation Strategies in Clinical AIIogeneic BMT Core A Administration and Biostatistics Core B Skin Analysis and Epidermal Engineering Core C Proteomic and Genomic Analyses